Columbium base alloy



United States Patent Ofiice 3,028,236 Patented Apr. 3, 1962 This invention relates to a columbium base alloy containing aluminum and vanadium as the major alloying ingredients.

The development. of rockets and missiles and advances in nuclear reactors and gas turbines necessitate the use of materials of construction capable of withstanding extreme operating conditions. It is necesassary under these conditions to have superior alloys which combine workability, high-temperature strength and high-temperature oxidation resistance.

Accordingly, it is an object of the present invention to provide an alloy which is characterized by resistance to hightemperature oxidation at temperatures in excess of 1000 C.

It is another object of the pt esent invention to provide an alloy which is amenable to heat treatment by conventional means.

Still another object of the present invention is to pro vide an alloy which, when subjected to an oxidizing atmosphcre at elevated temperatures, forms a pellicular metal oxide which adheres firmly to the alloy and is not substantially volatilized therefrom.

Other objects will be apparent from the subsequent disclosure and appended claims.

The alloy which satisfies the objects of the present invention consists essentially of 0.5 to 10 weight percent aluminum, 0.5 to 10 weight percent vanadium, up to 40 weight percent titanium, up to 30 weight percent chromium, up to 30 weight percent in the aggregate of at least one metal selected from the group consisting of tungsten and tantalum, up to 10 weight percent in the aggregate of at least one metal selected from the group consisting of manganese, nickel, iron, cobalt, zirconium and hafnium, up to 5 weight percent in the aggregate of at least one alloying element selected from the group consisting of barium, silicon, beryllium, yttrium, boron and the rare earth metals, and the remainder being columbium in a minimum amount of at least 30 weight percent.

In the foregoing alloys, the colubium contentis advantageously in excess of 45 percent and preferably in excess of 70 percent.

Even where the alloy has a very high columbium content, the addition thereto of small amounts of the aluminum and vanadium greatly enhances the alloys proper ties. For example, an alloy containing about 4 weight percent each of aluminum and vanadium, the balance being columbium and incidental impurities exhibits superior properties. If, in addition to the aluminum and vanadium, about 7 weight percent of titanium is added, the properties of the alloy are still further enhanced.

While the foregoing alloy satisfies all of the objects set forth above it has been found that an alloy consisting essentially of l to weight percent titanium, 1 to 15 weight percent chromium, l to 6 weight percent aluminum, 0.5 to 6 weight percent vanadium, up to weight percent in the aggregate of at least one metal selected from the group consisting of tungsten and tantalum, up to 5 weight percent in the aggregate of at least one metal selected from the group consisting of manganese, nickel, iron, cobalt, zirconium and hafnium. up to 3 weight percent in the aggregate of at least one alloying element selected from the group consisting of barium, silicon, eryllium, yttrium, boron and the rare earth metals, and

the remainder being columbium in a minimum amoun of at least 45 weight percent is particularly outstanding for use under oxidizing conditions and particularly hightemperature oxidizing conditions since the alloy strongly resists reaction with oxygen attemperatures in excess 01 1100 C.-

The maximum benefitsof the present alloy are obtained when the alloy consists essentially of from 5 to 20 weight percent titanium, 3 to 12 weight percent chromium, 2 to 6 weight percent. aluminum, 1 to; 5lweight percent vanadium, up to 30 weight percent in the aggregate of at least one metal selected from the group consisting of tungsten and tantalum, up to 5 weight percent in the aggregate of at least one metal selected from the group consisting of manganese, nickel, iron, cobalt, zirconium, and hafnium, up to 3 weight percent in the aggregate of at least one alloying element selected from the group consisting of barium, silicon, beryllium, yttrium, boron and the rare earth metals, and the remainder being columbium in a minimum amount of at least 50 weight percent.

Within the compositional ranges set forth above, certain specific compositions have been found to have exceptional properties. These compositions are shown in Table I which follows:

TABLE I Alloy Composition The alloys of the. present invention may be prepared by any number of methods such as the conventional methods using inert operating conditions, e.g., by the consumable arc-melting technique described in US. Patent No. 2,640,860, by non-consumable arc welding, by pressing and sintering of metallic powders or by other powder metallurgical processes. Great caution should be exercised to protect the metals from the atmosphere since contamination of the alloying mass by nitrogen and oxygen, etc. destroys many of the valuable properties of the alloy. To protect the alloying materials from these atmospheric contaminants the alloying operation should be performed under vacuum or in an inert atmosphere, such as argon or helium, or under a protective slag or under a combination of protective slag and controlled atmosphere. The final shaping of the alloy metal may be accomplished after cooling by any of several procedures, such as, extrusion, swaging, rolling or grinding the cast or sintered shape.

The examples provided below are prepared in a nonconsumable arc furnace such as that described by W. Kroll in Transactions of the Electra-Chemical Society, volume 78, 1940, pages 35 through 47. The procedure consists of placing the component metals on a water cooled, copper crucible shaped to retain the charge in a hearthlike depression and incorporated in a gas tight container supplied with a tungsten electrode capable of impressing an arc onto the charge. After careful evacuation of the system the charge was melted four times under an argon atmosphere until a homogeneous alloy of the desired composition was obtained.

The oxidation resistance of the alloy was determined by exposing highly polished specimens measuring approximately 1.60 x 0.85 x 0.65 centimeters to a stream of pure, dry oxygen within an air tight container. The specimens were suspended and heated in this atmosphere at 800 C., 1000 C., or l200 C. and the amount of pellicular metal oxide formed on the surfaces during the exposure was continuously me sured and recorded autozormpoEi! 3 maticaily by means of balances of the Mauer type. By this method an accurate rate of oxidation weight gain could be obtained for the alloys tested. The weight gain is expressed in milligrams of weight gained per square centimeter of surface exposed for at least 100 hours at the different temperatures.

EXAMPLE I EXAMPLE II Adopting the procedures described above, an alloy was prepared containing 57 percent columbium, 20 percent titanium, percent nickel, percent chromium, 4 percent aluminum, and 4 percent vanadium. Upon testing for its oxidation resistance, the 100 hour weight gain, expressed in milligrams per square centimeter, was found to be 5.85 at 800' C., 32.4 at 1000 C., and 189.4 at 1200' C.

EXAMPLE III Adopting the procedures described above, an alloy was prepared containing 60.2 percent columbium, 18.3 percent titanium, 3.3 percent nickel, 3.3 percent iron, 8.3 percent chromium, 3.3 percent aluminum, and 3.3 percent vanadium. Upon testing for its oxidation resistance, the 100 hour weight gain expressed in milligrams per square centimeter, was found to be 14.7 at 800 C., 30.5 at 1000 C. and 193 at 1200 C.

EXAMPLE IV Adopting the procedures described above, an alloy was prepared containing 63 percent columbium, 20 percent titanium, 9 percent chromium, 5 percent vanadium and 3 percent aluminum. Upon testing for its oxidation resistance, the 100 hour weight gain, expressed in milligrams per square centimeter, was found to be 12.5 at 800 C., 61.6 at 1000' C. and 184 at 1200 C.

EXAMPLEV Adopting the procedures described above, an alloy was prepared containing 63.5 percent columbium, 20 percent titanium, 9 percent chromium, 4 percent vanadium, 3 percent aluminum, and 0.5 percent zirconium. Upon testing for its oxidation resistance, the 100 hour weight gain, expressed in milligrams per square centimeter, was found to be 8.71 at 800' C., 69.7 at 1000 C. and 315 at 1200 C.

EXAMPLE VI Adopting the procedures described above, an alloy was prepared containing 46 percent columbium, 35 percent titanium, 8 percent chromium, 4 percent vanadium, 3 percent aluminum, and 4 percent manganese. Upon testing for its oxidation resistance, the 100 'hour weight gain, expressed in milligrams per square centimeter, was found to be 12.5 at 800 C., 134 at 1000' C. and 342 at 1200 C.

EXAMPLE VII Adopting the procedures described above, an alloy was prepared containing 53 percent columbium, 20 percent titanium, 3 percent vanadium, 3 percent aluminum, 3 percent chromium, 3 percent cobalt, 3 percent iron, 3 percent nickel, 3 percent silicon, 3 percent tantalum and 3 percent tungsten. Upon testing for its oxidation resistance, the 100 hour weight gain, expressed in milligrams per square centimeter was found to be 3.8 at 800 C., 23.8 at 1000 C. and 65.5 at 1200 C.

EXAMPLE VIII Adopting the procedures described above, an alloy was prepared containing 94 percent columbium, 3 percent aluminum and 3 percent vanadium. Upon testing for its oxidation resistance, the 100 hour weight gain, expressed in milligrams per square centimeter, was found to be 46 at 800 C. and 92.2 at 1000 C.

EXAMPLE X Adopting the procedures described above, an alloy was prepared containing percent columbium, 7 percent aluminum and 3 percent vanadium. Upon testing for its oxidation resistance, the hour weight gain, expressed in milligrams per square centimeter, was found to be 18.9 at 800 C. and 140 at 1000 C.

EXAMPLE XI Adopting the procedures described above, an alloy was prepared containing 70 percent columbium, 5 percent aluminum, 5 percent vanadium and 2 0 percent tantalum. Upon testing for its oxidation resistance, the 100 hour weight gain, expressed in milligrams per square centimeter, was found to be 24.2 at 800 C. and 122 at 1000 C.

EXAMPLE XII Adopting the procedures described above, an alloy was prepared containing 72 percent columbium, 5 percent aluminum, 5 percent vanadium and 20 percent titanium. Upon testing for its oxidation resistance, the 100 hour weight gain, expressed in milligrams per square centimeter, was found to be 13.6 at 800 C. and at 1000 C.

Although it is preferable to use high-purity metals in the preparation of the alloys of the present invention, a small amount of variance in purity can be tolerated before product quality suffers appreciably. The alloys of the working examples are prepared from commercially available metals which contain a small percentage of incidental impurities.

What is claimed is:

1. An alloy consisting essentially of from 1 to 25 weight percent titanium, 1 to 15 weight percent chromium, 1 to 6 weight percent aluminum, 0.5 to 6 weight percent vanadium, up to 30 weight percent in the aggregate of at least one metal selected from the group consisting of tungsten and tantalum, up to 5 weight percent in the aggregate of at least one metal selected from the group consisting of manganese, nickel, cobalt, iron, zirconium, and hafnium, up to 3 weight percent in the aggregate of at least one alloying element selected from the group consisting of barium, silicon, beryllium, yttrium, boron and the rare earth metals, the remainder being columbium in a minimum amount of at least 45 weight percent.

2. An alloy consisting essentially of from 5 to 20 weight percent titanium, 3 to 12 weight percent chromium, 2 to 6 weight percent aluminum, 1 to 5 weight percent vanadium, up to 30 weight percent in the aggregate of at least one metal selected from the group consisting of tungsten and tantalum, up to 5 weight percent in the aggregate of at least one metal selected from the group consisting of manganese, nickel, iron, cobalt, zirconium, and hafnium, up to 3 weight percent in the aggregate of at least one alloying element selected from the group consisting of barium, the rare earth metals, and the remainder being columbium in a minimum amount of at least 50 weight percent.

silicon, beryllium, yttrium, boron and 4. Analloy consisting essentially of about 10 weightpercent titanium,- about8 weight-percent chromium, about 4 weight percent vanadium, about 3 weight percent aluminum, the :balance :beingcolumbium and incidental impurities.

.5. An alloy consisting essentiallytoi about 20 weight percent titanium, about 9- weight percent chromium,

about 5: weight -percent vanadium,=about '4- weightpercent iron, about 3.-weight-per cent aluminum, the balance-be- .-ingcolumbium and incidental impurities.

r 6. alloyconsisting' essentially .of about 7 10 weight percent titanium,-about -9 'vveight-percent chromium, about 4 weight percentvanadium, about 3-Weightapercent aluminum, about"2-=weight-percent iron, the balancebeing columbium and .-incidental impurities.

7. An alloy consisting essentially of about 4 weight percent aluminum, about 4 weight percent vanadium, the balance being columbium and incidental impurities.

8. An. alloy consisting essentially of about 7 weight 5 percent titanium, about 4 weight percent aluminum, about 4 weight percent vanadium, the balance being columbium and incidental impurities.

9. An alloy consisting essentially of from .5 to 10 weight percent aluminum, from .5 to lO-wveight percent 1 vanadium, .the balance being columbium-and incidental impurities.

References Cited in the file-of this patent UNITED STATES PATENTS 15 2,822,268 -Feb. 4, 1958 2,838,395 "Rhodin June 10, 1958 2,838,396 Rhodin June 10,1958

. 2,860,970 Thielemann Nov. 18, 1958 2,882,146 'Rhodin Apr. 14, 1959 Wainer Apr. 21, 1959 

1. AN ALLOY CONSISTING ESSENTIALLY OF FROM 1 TO 25 WEIGHT PERCENT TITANIUM, 1 TO 15 WEIGHT PERCENT CHROMIUM, 1 TO 6 WEIGHT PERCENT ALUMINUM, 0.5 TO 6 WEIGHT PERCENT VANADIUM, UP TO 30 WEIGHT PERCENT IN THE AGGREGATE OF AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF TUNGSTEN AND TANTALUM, UP TO 5 WEIGHT PERCENT IN THE AGGREGATE OF AT LEAST ONE METAL SELECTED FROM THE GROUP CONSISTING OF MANGANESE, NICKEL, COBALT, IRON, ZIRCONIUM, AND HAFNIUM, UP TO 3 WEIGHT PERCENT IN THE AGGREGATE OF AT LEAST ONE ALLOYING ELEMENT SELECTED FROM THE GROUP CONSISTING OF BARIUM, SILICON, BERYLLIUM, YTTRIU, BORON AND THE RARE EARTH METALS, THE REMAINDER BEING COLUMBIUM IN A MINIMUM AMOUNT OF AT LEAST 45 WEIGHT PERCENT. 